Low Expansion Borosilicate Glass (ASTM E438 Type I Class A)
Low expansion borosilicate is a grade of borosilicate glass. The graph bars on the material properties cards below compare low expansion borosilicate to other glass and glass-ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Compressive (Crushing) Strength
2000 MPa 290 x 103 psi
Elastic (Young's, Tensile) Modulus
68 GPa 9.9 x 106 psi
Flexural Strength
69 MPa 10 x 103 psi
Fracture Toughness
0.8 MPa-m1/2 0.73 x 103 psi-in1/2
Knoop Hardness
510
Poisson's Ratio
0.21
Tensile Strength: Ultimate (UTS)
280 MPa 41 x 103 psi
Thermal Properties
Maximum Temperature: Mechanical
360 °C 680 °F
Maximum Thermal Shock
160 °C 320 °F
Melting Onset (Solidus)
560 °C 1040 °F
Specific Heat Capacity
830 J/kg-K 0.2 BTU/lb-°F
Thermal Conductivity
1.2 W/m-K 0.68 BTU/h-ft-°F
Thermal Expansion
3.3 µm/m-K
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 MHz
5.4
Dielectric Strength (Breakdown Potential)
5.0 kV/mm 0.2 V/mil
Electrical Dissipation At 1 MHz
0.0046
Electrical Resistivity Order of Magnitude
9.0 10x Ω-m
Otherwise Unclassified Properties
Density
2.2 g/cm3 140 lb/ft3
Light Transmission Range
0.3 to 2.5 µm
Refractive Index
1.5
Common Calculations
Stiffness to Weight: Axial
17 points
Stiffness to Weight: Bending
61 points
Strength to Weight: Axial
35 points
Strength to Weight: Bending
43 points
Thermal Diffusivity
0.63 mm2/s
Thermal Shock Resistance
91 points
Followup Questions
Further Reading
ASTM E438: Standard Specification for Glasses in Laboratory Apparatus
Dictionary of Glass: Materials and Techniques, Charles Bray, 2002
Glass: Mechanics and Technology, Eric Le Bourhis, 2007
Handbook of Optical Constants of Solids, Edward D. Palik (editor), 1998
Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012